Street



(No Model.)

W. n. B'RADSTREET. ENVELOP.

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IVILLIAM D. BRADSTREET, OF IVALTHAM, MASSACHUSETTS, ASSIGNOR TO ABBIE D. HANKERSON, OF SAME PLACE.

ENVELOP.

SPECIFICATION forming part of Letters Patent No. 577,571, dated February 23, 1897. Application filed December 14, 1896. Serial No. 615,692. (No model.)

To all whom it may concern.-

Be it known that I, WILLIAM D. BRAD- STREET, a citizen of the United States, residing at \Valtham, in the county of Middlesex and State of Massachusetts, have invented a Self-Adj usting Expansible Envelop, of which the following is a full, clear, and exact description, reference being had to the accompanying drawings, making part of this specification, in which--- Figure 1 is a perspective view of an envelop constructed in accordance with my invention. Fig. 2 is a perspective view of the same expanded to increase its capacity. Fig. is a section on the line 3 3 of Fig. 2. Fig. 4152111 enlarged sectional detail on the line 4 a of Fig. 1.

My invention has for its object to provide a self-adjusting envelop of simple construction which is capable of being expanded within certain limits to increase its capacity; and to this end my invention consists in an envelop having two adjoining flaps fastened together by means of a sliding connection which permits the envelop to expand and ad just itself to the thickness of the papers or articles placed therein, as hereinafter more fully set forth.

In the said drawings, A represents an envelop preferably composed of strong and stiff material, such as thick paper or paper having a cloth lining, to adapt it for use in filing away documents or papers or containing bulky articles.

b I) represent the end or side flaps, c the lower flap or back, and d the upper or closing flap, which may be provided, if desired, with a tape or other suitable fastening device for holding it in place when folded over to close the envelop. Each of the end flaps Z; is adjustably secured to the lower flap c by means of an eyelet or flanged rivet f, which slides in a slot or track g, formed in the underlying portion of the lower flap c, the inner flange of the eyelet lapping the edges of the slot g, whereby the end flaps are held securely to the lower flap while sliding thereupon, the ends of said slots forming stops to limit the movement of the eyelets or rivets therein. By

means of the sliding connections above dedered self-adjusting, so that it will expand, as shown in Fig. 2, to any desired degree w'rthin the limits of the slots g for the reception of bulky papers or other articles which it may be desired to placewithin it, thus especiall y adapting it for filing away documents, as it will lie comparatively fiat when a few papers only are placed within it, and asmore papers are added the end flaps will automatically slide back on the lower flap to proportionately increase its capacity, while as papers are withdrawn the thickness of the envelop can be correspondingly diminished.

The top flapd is preferably made large and square to cover the contents of the envelop when expanded. The end flaps may overlie or underlie the lower flap, as preferred, and each of the end flaps may be secured'to the lower flap by two or more sliding connections instead of one, for additional strength, if desired. Instead of both end flaps being adj ustably secured to the lower flap, as described, one only of said flaps may be so secured, the other being rigidly fastened in place. I prefer, however, to make both end flaps adjustable, as such construction increases the expansibility of the envelop.

It is obvious that the construction of the sliding connections between the end flaps and the lower flap may be varied, as any suitable fastening device which will secure the end flap to the lower flap in such manner as to permit the one to slide on the other may be employed without departing from the spirit of my invention.

Instead of connecting either or both of the end flaps b with'the lower flap 0, the two end flaps may be extended to lap one another and be adjustably secured together by means of a suitable sliding connection which will permit the envelop to expand in substantially the same manner as previously described.

What I claim as my invention, and desire to secure by Letters Patent, is-

1. In an envelop, the combination with the lower flap or back, of an end flap secured to the lower flap by a sliding fastening device, whereby the envelop is made expansible to vary its capacity, said fastening device being scribed it will be seen that the envelop is renprovided With a stop to limit the expansito vary the capacity of the envelop, substan- [o bility of the envelop, substantially as detially as described. scribed. WVitness my hand this 12th day of Decen1- 2. Aself-adjnsting expansible envelophavber, A. D. 1896.

. ing an end flap adj ustably secured to the lower WILLIAM D BRADSTREET flap or back by means of a rivet or projection on the one part, and a slot or track on the In presence ofother part, whereby the two connected parts P. E. TESOHEMAOHER, are permitted to slide the one upon the other B. L. MARDEN. 

